Improvement in hot-air furnaces



1. :E. GRANT.

Hot-Air Furnace. No. 11,770.

Patented 06L 3, 1854.

N. PETERS. Pboln-um ra hur. Wnhingmn. n C.

NITED STATES PATENT OFFICE.

JOHN E. GRANT, OF CI'IARLESTOWN, ASSIGNOR TO CYRUS CARPENTER AND A. D. SHAW, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN HOT-AIR FURNACES.

Specification forming part of Letters Patent No. 11,770, dated October 3, 1854.

To all whom it may concern.-

Be it known that I, JOHN E. GRANT, of Charlestown,in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvement in Hot-Air Furnaces; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the annexed drawings, and to the letters of reference thereon marked, in which similar letters refer to similar parts.

Figure l is a vertical section on the line a b of Fig. 2, which is a plan with the top of the outside casing A, the top of the inside casing B, and the dome-plate C removed to show the interior of the furnace. Fig. 3 is a vertical section of the furnace on the line 0 (Z of Fig. 2 on a portion of the base with both inside and outside casings removed. Fig. 4 is a front elevation, Fig. 5 is a plan, and Fig. 6 a rear elevation, of the deflecting-plate E.

The nature of my invention consists in interposin g a deflecting-plate between the gases liberated by the usual partial combustion of fuel in the lire-pots of furnaces'and the smokepipe by which they are conducted off in such a manner that the gases liberated shall be constrained to circulate within the radiatingchamber, that they may receive during their circulation an admixture of air to conduce to theircombustion.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

Upon a base or foundation D is placed the ash pit or box Z, in which the revolving grate e is hung and upon which is placed the firepot N. Resting upon the fire-pot is the conical chamber S, to which the furnace-mouth L and smoke-outlet f are attached or cast. In a recess formed by the flange 7t stands a deflecting-plate E, before the outlet f and opposite the door V. On the plate E are the flangesz' i and 71, the purpose of which will be explained hereinafter. The chamber R is placed on the chamber S and covered by the plate 0, finishing the combustion-chamber. Upon the base D is built a brick casing 3, surrounding the stove.

P is a directing-plate extending from the casing B and surrounding the fire-pot. The hotair chamber surrounding the radiatingsurfaces of the stove is a space formed between the casing B, the plate P, and the radiating-surfaces. The casing A, surrounding the inner casing B, is built upon the base D, leaving the dead-air space 0 between thecasings and above the plate P.

'7 T are inlets for the admission of cold air, and I I are outlets for the egress of heated air.

U is an air-space formed between the out side door-frame G and the casings M and B.

H is the door-frame of the man-hole.

V is the inner feed-door; W, the outer feeddoor; X, the ash-pit door, and Y the manhole door.

f is the outlet of the stove, on which is joined the branched pipe J having at one end the damper g, while on the branch 19 the funnel K is joined.

F is the box through which the supply of cold air enters.

Z Z, &c., are sand-joints. 7

Having thus described the construction of my furnace, I will now proceed to show its operation. The fire being kindled in the firepot, the air necessary to support combustion flows in through the door X, ash-pit, and grate. The rarefied gases liberated by combustion rise and would pass off through the outletf were they not prevented by the plate E. This plate E may be constructed of sheet or cast metal, fire-brick, soapstone, or other suitable material. Its form may be adapted to the shape of the furnace to which it may be applied if the principle of its application be preserved. I place the outlet fnear the surface of the fire, or comparatively low in relation to the height of the furnace. It is not necessary that the outlet should be opposite the mouth of the furnace, as it may vary with the requirements of the location, the plate E being always placed directly in front of the outlet f. In the example furnished by the model the plate E is placed opposite the door and in front of the outlet f, for the purpose of deflecting the gases from the outlets and causing them to rise and circulate in the space above the fire, formed by the dome-plate C and the hollow truncated cones R and S, which space for the convenience of reference I will term the radiating-chamber. The rarefied gases and the light unconsumed particles of fuel circulating within the radiatingchainber will receive an admixture of air through the door V or a pipe which may be introduced to furnish the supply of air requisite to complete the combustion of the gases. The resultants of the combustion of the liberated gases in the radiating-chamber, having a greater specific gravity than the gases before combustion, will descend and pass off at the outlet through the space formed by the plate E, its flanges t' 'i and h, and the sides of R and S. The saddle-flange h serves to divide the escaping current, causing it to make a circuitous course and retarding it during its exit, by which the heat containedin it will be more thoroughly abstracted. The cold air ispermitted to pass through the cold-air box F, the casing A, and the inner holes TT, &c., into the space bounded by the plate P, the casing B, and the foundation, and from thence through the annular space formed between the flange of the plate P and the fire-pot. The air, becoming partially heated, ascends in perpendicular lines and receives the heat radiated from the heating-surfaces before passing off at the exit-pipes I I. The draft is regulated by admitting more or less air through the pipe J by means of the damper 9, instead of checking the supply of air to the fire by closing the ash-pit door, thereby deadening the fire.

Among the advantages which I- have ob tained by the use of the deflecting-plate stands prominently the simplicity with which a furnace may be constructed that will consume all fuel with which it is supplied and not allow a large portion of it to pass off in smoke, as is the case With most hot-air furnaces. The thorough combustion and slow circulation in the radiating-chambers attained by the intervention of the deflecting-plate insure a power and economy of heating not obtained by any complication of small or Winding pipes and narrow passages, which require a powerful draft and are necessarily difficult of construction and very liable to derangement.

What I claim as new, and desire to secure by Letters Patent, is

The deflecting-plate E, with its saddleflange h, when interposed in the combustion chamber between the products of combustion and exit-pipe, in the manner and for the purpose herein described' In testimony that the above is a correct specification I have hereto set my signature this 27th day of May, 1854.

JOHN E. GRANT.

Witnesses:

J. B. CROSBY, JEREMIAH R. OOALLAGHAN. 

